1. Field of the Invention
The invention relates in general to liquid crystal displays, and more particularly to liquid crystal displays and the driver chips of the liquid crystal displays having dual transmitting modes.
2. Description of the Related Art
FIG. 1 shows a conventional liquid crystal display (LCD). LCD 100 includes timing controller 102, n driver chips 104 that are cascaded together, display panel 108, PCB (print circuit board) 106, and glass substrate 110. The timing circuit 102 on PCB 106 is used for outputting pixel signals that are in single-ended type. The first driver chip 104(1) is electrically connected to the timing controller 102. Driver chips 104(1), 104(2), 104(3) . . . 104(n) are cascaded together. After diver chip 104(1) receives the pixel signal from the timing controller 102, the pixel signal is sent to driver chip 104(2); driver chip 104(2) then in turn sends this pixel signal to the next driver chip 104(3), and continues in this fashion until the pixel signal is being sent to the last driver chip 104(n). Each driver chip 104 drives panel 108 according to the captured pixel signal. Each driver chip 104 is disposed on the glass substrate 110, and such layout on the glass substrate is referred to as chip on glass (COG).
FIG. 2 shows a conventional driver chip. Between the driver chip 104, the pixel signals are being transmitted in single-ended type. Driver chip 104 includes single-ended receiver 111, single-ended transmitter 112, shift register 113, and pixel driver 114. Single-ended receiver 111 and single-ended transmitter 112 are for example CMOS TTL circuits. Single-ended receiver 111 first receives pixel data, then sends the pixel data to shifter register 113, then shift register 113 in turn sends the pixel data to single-ended transmitter 112 for outputting to next driver chip. Pixel driver 114 retrieves data corresponding to the driver chip from shift register 113 of the chip, and uses the retrieved data to drive the display panel 108.
However, due to the large impedances of glass substrate conducting wires, the pixel signals are severely attenuated when being transmitted through the glass substrate conducting wires disposed between the driver chips. Especially for high resolution LCDs, the number of driver chips required are even greater, and the signal attenuation problem becomes more severe, since the signals have to travel a greater distance, and the application of this type of layout in high resolution LCDs remains a difficult issue.